diff --git a/tools/testing/selftests/net/amt.sh b/tools/testing/selftests/net/amt.sh
index 3ef209cacb8e..663744305e52 100755
--- a/tools/testing/selftests/net/amt.sh
+++ b/tools/testing/selftests/net/amt.sh
@@ -73,6 +73,8 @@
 #       +------------------------+
 #==============================================================================
 
+source lib.sh
+
 readonly LISTENER=$(mktemp -u listener-XXXXXXXX)
 readonly GATEWAY=$(mktemp -u gateway-XXXXXXXX)
 readonly RELAY=$(mktemp -u relay-XXXXXXXX)
@@ -246,14 +248,15 @@ test_ipv6_forward()
 
 send_mcast4()
 {
-	sleep 2
+	sleep 5
+	wait_local_port_listen ${LISTENER} 4000 udp
 	ip netns exec "${SOURCE}" bash -c \
 		'printf "%s %128s" 172.17.0.2 | nc -w 1 -u 239.0.0.1 4000' &
 }
 
 send_mcast6()
 {
-	sleep 2
+	wait_local_port_listen ${LISTENER} 6000 udp
 	ip netns exec "${SOURCE}" bash -c \
 		'printf "%s %128s" 2001:db8:3::2 | nc -w 1 -u ff0e::5:6 6000' &
 }